UC Davis' Bohart Museum of Entomology has television's "Fear Factor" to thank. Some 30-40 Madagascar hissing cockroaches, left over from one of the show's outrageous stunts, were passed on last year to the museum, and now make up part of its 30-year-old hissing cockroach collection.

The hissing cockroaches (Gromphadorhina portentosa), are native to the island of Madagascar off the coast of Africa. They are among the world's largest roaches, measuring two to three inches long and an inch wide -- about the size of a small mouse.

In the forest, they live in rotting logs, feeding on fallen fruit and fecal matter. At the Bohart Museum, the "hissers" dine on fruits and vegetables, preferring apples, lettuce and yams.

For people considering keeping roaches for pets, the Madagascan cockroaches are easy to care for.

"You just add food and you get more," says entomologist Lynn Kimsey, director of the Bohart Museum. "They move slowly, are docile, emit little or no odor, and do not bite."

The Madagascan roaches hiss defensively when disrupted or threatened, by forcing air through a pair of modified abdominal spiracles, or pores, which are part of their respiratory system. Male roaches also hiss during courtship and mating.

Cockroaches are considered "living fossils" because they have survived on Earth some 250 million years, appearing long before dinosaurs. More than 3,500 species of cockroaches exist today.

The Bohart Museum, founded in 1946, houses some 7 million specimens in its worldwide collection, which focuses on terrestrial and freshwater invertebrates. It also is home to the California Insect Survey, a storehouse of the insect biodiversity of California's deserts, mountains, coast and Central Valley.

The museum is open weekdays from 8:30 a.m. to noon and 1 to 5 p.m. Group tours can be arranged with senior museum scientist Steve Heydon at (530) 752-0493 or by e-mailing the museum at bmuseum@ucdavis.edu.

The museum's Web site is at http://bohart.ucdavis.edu.